The present invention relates to disc storage systems for storing information. More specifically, the present invention relates to sliders used in such systems.
Disc drives are used for storing information, typically as magnetically encoded data, and more recently as optically encoded data, on a disc surface. A transducing head is carried on a air-bearing slider that rides on a bearing of air above the disc surface as the disc rotates at high speed. In another technique, the slider contacts the disc surface with no air bearing interface such as is shown in U.S. Pat. Nos. 5,453,315 and 5,490,027. The head is then positioned radially over the disc to read back or write at a desired location. Benefits associated with an air bearing design are lost in such "contact" sliders.
In an air bearing design, the air bearing provides an interface between the slider and the disc which prevents damage to the disc over the life of the system, provides damping if the disc drive system undergoes shock due to external vibrations. The air bearing is also used to provide a desired spacing between the transducing element and the disc surface. A bias force is applied to the slider by a flexure armature in a direction toward the disc surface. This bias force is counteracted by lifting forces from the air bearing until an equilibrium is reached. The slider will contact the disc surface if the rotating speed of the disc is insufficient to cause the slider to "fly." This contact typically occurs during start up or shut down of the disc. If the slider contacts a region of the disc which carries data, the data may be lost and the disc permanently damaged.
In many disc drive systems, a lubricant is applied to the disc surface to reduce damage to the head and the disc surface during starting and stopping. Air or gas also acts as a lubricant. However, a phenomenon known as "stiction," which is caused by static friction and viscous shear forces, causes the slider to stick to the disc surface after periods of non use. The lubricant exasterbates the stiction problem. The stiction can damage the head or the disc when the slider is freed from the disc surface. Additionally, the spindle motor used to rotate the disc must provide sufficient torque to overcome the stiction.
One technique used to overcome the problem associated with stiction is to provide texturing to at least a portion of the disc surface. However, this reduces the effective recording area of the disc. Additionally, various attempts have been made to provide texturing on the air bearing surface of the slider. For example, U.S. Pat. Nos. 5,079,657 and 5,162,073 describes a technique for forming recesses in a slider surface. Another technique which is described in U.S. Pat. No. 5,418,667 includes providing large pads which provide a pitch to the slider to allow air flow between the air bearing surface and the disc.